Expansion joint

ABSTRACT

An expansion joint support system preferably having the form of a plate link chain attached through pin studs to expansion folds which provides equal and uniform distribution of motion and stresses during elongation or compression.

C Umted States Patent [1 1 [111 3,917,320

Grosse-Allermann Nov. 4, 1975 EXPANSION JOINT 2,196,676 4/1940 Johnson et 31.... 285/226X m1 52%;"??? 2,1122; 1225;211:6- 22222;

Germany [73] Assignee: Babcock & Wilcox, Limited,

London, England Filed: Jan. 18, 1974 Appl. No.: 434,462

US. Cl 285/114; 285/226 Int. Cl. F16L 13/04 Field of Search 285/114, 301, 227, 226,

References Cited UNITED STATES PATENTS 8/1934 Zallea 285/301 Primary Examiner--Dave W. Arola Attorney, Agent, or FirmJ. M. Maguire ABSTRACT An expansion joint support system preferably having the form of a plate link chain attached through pin studs to expansion folds which provides equal and uniform distribution of motion and stresses during elongation or compression.

2 Claims, 5 Drawing Figures US. Patent Nov. 4, 1975 Sheet 1 of 2 3,917,320

US. Patent Nov. 4, 1975 Sheet 2 of2 3,917,320

EXPANSION JOINT This invention relates to an expansion joint for ducts or pipes made of expansible bellow type folds and, more particularly, for a vertical arrangement .of a duct, in which the expansion ties are attached at the outer circumference of each bellow type fold to limit the maximum motion.

Multifold expansion joints are generally preferred in the absorption of large expansion movements. To limit the motion of the expansion joint, special anchors are usually provided at the ends of the expansion joint. During the compression or extension of a multifold joint, it is possible that some of the folds are compressed or extended more that others, due to the type of anchors usually provided. The folds with larger movement run into the danger of being stressed above the elasticity limit, which in time, could cause brittleness and failure.

An expansion joint for vertical sheet ducts has the folds arranged one above the other. The weight of the upper folds causes additional loads on the folds below such that the upper folds tend to elongate while the lower folds tend to be compressed. This results in a non-uniform loading of the expansion folds. Subsequently, an extension of the expansion joint increases the elastic tension stresses of the upper folds while the elastic tension stresses of the lower folds are decreased. correspondingly, a compression of the expansion joint reduces the elastic compression stresses of the upper folds while those of the lower folds are increased. Therefore, only the extreme folds, those which experience the greatest tension and compression stresses, can be utilized to the allowable design limit.

The purpose of this invention is to provide means for equal and uniform distribution of motion and stresses to every fold of an expansion joint during elongation or compression. Also, the weight of each fold is separately and independently suspended when installed on vertical ducts.

According to this invention a support system is provided in the form of a chain, preferably a link chain of overlapping plates. The chain is connected to the folds by means of pin studs, attached at one end to channel section members welded to the folds, and inserted through openings in the plates. The end plates are provided with at least one elongated opening and, the intermediate links are provided with at least one elongated opening and one circular opening. These openings are suitably sized so as to provide slideable contact with the pin stud inserted therethrough. Also, the elongated openings are sized so as to provide limited travel of the plate relative to the pin stud.

The ends of the plate link chain are so connected to the expansion joint support frame that a tension or compression force from the support frame is exerted on the first link and the rest of the links extend or contract from fold to fold in the axial direction of the expansion joint. Because one stud opening of each link plate is circular and the overlapped stud opening is elongated the overlapped link plate follows the movement of that fold which has its pin inserted into the circular opening of the overlapped link plate. The elongated opening permits the sliding of the link plate relative to the fold until the pin stud of that fold touches one of the ends of the elongated opening. Thus, the length of the elongated 2 opening limits the movement of the link and also the range of extension of each fold.

The length of the elongated openings in the link plates should correspond to the range of allowable movement of each fold. In this way, the movements and stresses of the folds in the extended and compressed state are distributed uniformly to all folds of the expansion joint. When the pin studs of the chain bear on the ends of the elongated openings, tension or compression forces from and through the pins can be transferred by the chain to the supports. v

In a vertical arrangement when the expansion joint is compressed, the links are in their contracted position and the weight of each fold is supported through the links on the lower support frame. In an extended position of the expansion joint the links are also extended and the weight of the folds is supported through sus-- pension from the upper support frame. In a partially extended stage of the expansion joint the upper folds can be extended while the lower folds are contracted. However, through proper dimensioning of the elongated opening the allowable stress limit of the folds is not ex- I pin stud so that the link plates can follow the curvatureof the bend. In special cases it may be advantageous to properly bend the individual link plates.

The expansion folds receive a maximum compression at the inside radius of the bend and a maximum extension at the outside radius. Again, through proper dimensioning of the elongated openings, the allowable motions and stresses of each fold are not exceeded. Each fold is uniformly stressed when the expansion joint is fully bent to its design angle, and the extended length of the link chain limits the length of the outer are so that an evading movement of folds. sidewards is avoided.

An example of the application of this invention is shown on the attached drawings and is explained in the following paragraphs.

FIG. 1 shows a partial cross section through an expansion joint in a compressed state with a chain link arrangement at the outside circumference.

FIG. 2 shows a partial cross section through another part of an expansion joint in an extended state and with the link chain arranged to be suited for toggle action.

FIG. 3 represents an intermediate link plate of a chain.

FIG. 4 represents an end link plate of a chain.

FIG. 5 shows a partial view of the link chain connected to the folds.

An expansion joint, according to FIGS. 1 and 2, is provided in a vertical duct of large cross section to compensate for the axial expansion of the duct. The expansion joint consists of expandable folds 1 made of steel plate and are connected to each other in series. At the upper end 2 of the expansion joint there are supports 3 distributed at the periphery and attached to the frame. At the lower end 4 there are also supports 5 attached in the same manner. Each upper support 3 is connected to the lower support 5 through a link chain 6 which is arranged parallel to the axis of the duct and close to the outside of the folds. The chain 6 consists of overlapped end link plates 7 and 8 and intermediate link plates 12. Also, the end link plates 7 and 8 are connected to the supports 3 and respectively in such a way that tension or compression forces are transferred through either link plate. In FIG. 1 the link plates 7 and 8 are welded to supports 3 and 5 respectively. In FIG. 2 the end plates 7 and 8 are welded to plates 9 which are embedded in rubber bumpers 10 that are enclosed in a steel pan 1 1 which is attached to the supports 3 and 5. Due to the elasticity of the rubber bumpers, it is possible to swing the end links in all directions to some degree. Tension or compression forces are also transferred through this type connection.

The end links 7 and 8 and the intermediate links 12 are made of flat bar or plate and are provided with openings 13 through which pin studs 14, attached to the outer periphery of the folds 1, are inserted. The openings in the end link plates 7 and 8 are made elongated by milling to a predetermined length 15 (FIG. 3) and, one of the two openings of the intermediate link plate 12 is also made elongated by milling to a predetermined length 16 (FIG. 4). The other opening 13 in the intermediate links is circular.

The link chain 6 is then constructed such that the pin stud, attached at one end to a channel section connected to the outer periphery of a fold, is inserted through a circular opening of one link and through the elongated opening of the overlapping link. The process being continued throughout the chain until reaching the end plates. Because both end plates have elongated openings, one end plate will overlap a circular opening and the other end plate will overlap an elongated open mg.

The elongated openings permit the link chain 6 to elongate or to shorten, without transmitting any force, by relative movement of the pin in the opening. The length 15 and 16 of the elongated openings serve to limit free shortening or elongation of the chain from support 3 to support 5 along the distances l8 and 19. The free contraction or elongation of the distances l8 and 19 are thus determined by the lengths l5 and 16 v respectively. Therefore, the free expansion motion of each fold is limited by the length of the elongated openmg.

In FIG. 1 the expansion joint is shown in a compressed state. The support 5 has moved up the link 8 so that the pin stud 14 touches the bottom of the elongated opening and a force is exerted on the pin stud, This action has limited the contraction of the distance 18 for the lower fold. The pin stud touches the elongated opening in the link 12 which transfers the force from the pin stud to the link 12 above the stud. This limits the contracted distance between the lower fold and the adjoining fold. This action proceeds upwards until it reaches the pin stud of the upper fold. Because the pin stud 14 does not touch the ends of the elongated opening in the end link 7 there is no transfer of force to the support 3. In this manner, the entire link chain 6 is supported from the support 5 which also supports, from bottom up, all the folds 1 at an equal distance 19 without exceeding the allowable contraction for each fold.

The. plate links in FIG. 2 have an axial play along the pin studs 14 so that the link chain 6 can follow the relative change of direction of the duct ends 2 and 4.,The construction of the chain link 6 shown on FIG. 2 is suited for expansion joints used for bending during toggle action in which the sum of the allowableextensions of the folds 1 correspond to the elongation of the distance 19 along the external arc of the bent expansion joint, while the sum of the allowable contraction ofthe distance 19 along the inner arc of the bending curvature. The link chain serves to distribute the extensions and contractions uniformly on each fold and, in addition, prevents the distortion of the folds 1 due to the tendency of the folds to avoid bending.

While in accordance with provisions of the statutes there is illustrated and described herein a specific embodiment of the invention, those skilled in the art will understand that changers may be made in the formof,

the invention covered by the claims, and that certain features of the invention may sometimes be used to advantage without a corresponding use of the otherfeatures.

The embodiments of the invention in which an exclusive property or privilege are defined as follows:

1. A support .system for an expansion joint comprised of a plurality of serially connected expandable folds, a stationary frame connected at one end of the expansion joint and a movable frame connected at the opposite end thereof, a chain extending between the frames and including a plurality of intermediate links and a pairof terminal links, the intermediate links having overlapping ends and the terminal links having one end over-' lapping the adjacent'intermediate link,.means connecting the other end of each of said terminal links to the frame adjacent thereto, wherein each end of each pair of overlapping ends is disposed opposite one of the folds and formed with an opening, said openings being i in substantialalignment, and wherein at least one of the openings is elongated, a pin stud extending through said aligned openings to slideably interconnect the overlapping ends, and means connecting the pin stud to a corresponding fold and wherein said elongated opening of each pair of overlapping ends is closed at its opposite ends which limits the relative movement of its corresponding pin stud and links thereby limiting expansion and contraction of said joint.

2. A support system according to claim 1 wherein the means connecting each terminal link to the adjacent frame includes a rubber bumber attached to the frame, said terminal link being swively engaged with the bumber. 

1. A support system for An expansion joint comprised of a plurality of serially connected expandable folds, a stationary frame connected at one end of the expansion joint and a movable frame connected at the opposite end thereof, a chain extending between the frames and including a plurality of intermediate links and a pair of terminal links, the intermediate links having overlapping ends and the terminal links having one end overlapping the adjacent intermediate link, means connecting the other end of each of said terminal links to the frame adjacent thereto, wherein each end of each pair of overlapping ends is disposed opposite one of the folds and formed with an opening, said openings being in substantial alignment, and wherein at least one of the openings is elongated, a pin stud extending through said aligned openings to slideably interconnect the overlapping ends, and means connecting the pin stud to a corresponding fold and wherein said elongated opening of each pair of overlapping ends is closed at its opposite ends which limits the relative movement of its corresponding pin stud and links thereby limiting expansion and contraction of said joint.
 2. A support system according to claim 1 wherein the means connecting each terminal link to the adjacent frame includes a rubber bumber attached to the frame, said terminal link being swively engaged with the bumber. 